Chastity device discussions and reviews discussion

Hello! I searched for advice on “stretching the testicles while keeping a chastity device in place” but didn’t quite hit the mark. There was plenty of information about men whose scrotums were too tight and needed stretching before their cages would fit correctly. What I need is help with my husband having his sac stretched by an inch or two (or even five, haha!), while still staying locked up! He currently uses a Birdlocked, but will switch to a Jail Bird in a few weeks. So something that works well alongside the Jail Bird would be ideal. Does anyone have experience/recommendations for ball-sack-stretching devices worn together with being caged and where is a good place to buy them?